In vitro tests will be used to assess mutagenic potential (as opposed to alterations induced by pH changes alone) of a chemical entity which forms a portion of a new chemical contraceptive. Little is known about the safety of this chemical entity and a rapid in vitro screen for mutagenic activity would be useful. It is necessary to determine the effect of pH adjustment of the culture medium before and after the addition of the S-9 activation system. This will permit an assessment of the critical nature of pH adjustment before and after activation.